[v3,0/3] Add lockdep_assert_not_held()

Some kernel functions must not be called holding a specific lock. Doing
so could lead to locking problems. Currently these routines call
lock_is_held() to check for lock hold followed by WARN_ON.

Adding a common lockdep interface will help reduce the duplication of this
logic in the rest of the kernel.

Add lockdep_assert_not_held() to be used in these functions to detect
incorrect calls while holding a lock.

lockdep_assert_not_held() provides the opposite functionality of
lockdep_assert_held() which is used to assert calls that require
holding a specific lock.

The need for lockdep_assert_not_held() came up in a discussion on
ath10k patch. ath10k_drain_tx() and i915_vma_pin_ww() are examples
of functions that can use lockdep_assert_not_held().

Link: https://lore.kernel.org/lkml/37a29c383bff2fb1605241ee6c7c9be3784fb3c6.1613171185.git.skhan@linuxfoundation.org/
Link: https://lore.kernel.org/linux-wireless/871rdmu9z9.fsf@codeaurora.org/

This patch series adds lockdep_assert_not_held() and uses it in the
second patch in ath10k_drain_tx() function.

Changes since v2:
-- Fixed coding style issues
-- Patch 2 uses new lock states in __lock_is_held() and
   lock_is_held_type

Patch 1 incorporates suggestions from Peter Zijlstra on v1 series
to avoid misfires when lockdep_off() is employed.

Patch 2 Johannes Berg's suggestions as it make it easier to read and
maintain the lock states. These are defines and a enum to avoid changes
to lock_is_held_type() and lockdep_is_held() return types.

Patch 2 is a separate patch because it adds defines to lockdep.h and
kernel/locking/lockdep.c now includes lockdep.h - decided make this
a separate patch just in case issues related to header dependencies
pop up. I can combine Patches 1&2 if that is preferred.

Patch 3 uses the new interface in ath10k_drain_tx() function. Added
Kalle Valo's Ack from v1 for this change.

Tested on the mainline from yesterday.

Shuah Khan (3):
  lockdep: add lockdep_assert_not_held()
  lockdep: add lockdep lock state defines
  ath10k: detect conf_mutex held ath10k_drain_tx() calls

 drivers/net/wireless/ath/ath10k/mac.c |  2 ++
 include/linux/lockdep.h               | 18 +++++++++++++++---
 kernel/locking/lockdep.c              | 15 ++++++++++-----
 3 files changed, 27 insertions(+), 8 deletions(-)

On Fri, Feb 26, 2021 at 05:06:57PM -0700, Shuah Khan wrote:
> Shuah Khan (3):

>   lockdep: add lockdep_assert_not_held()

>   lockdep: add lockdep lock state defines

>   ath10k: detect conf_mutex held ath10k_drain_tx() calls


Thanks!

Peter Zijlstra <peterz@infradead.org> writes:

> On Fri, Feb 26, 2021 at 05:06:57PM -0700, Shuah Khan wrote:

>> Shuah Khan (3):

>>   lockdep: add lockdep_assert_not_held()

>>   lockdep: add lockdep lock state defines

>>   ath10k: detect conf_mutex held ath10k_drain_tx() calls

>

> Thanks!


Via which tree should these go?

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

On Mon, Mar 01, 2021 at 10:45:32AM +0200, Kalle Valo wrote:
> Peter Zijlstra <peterz@infradead.org> writes:

> 

> > On Fri, Feb 26, 2021 at 05:06:57PM -0700, Shuah Khan wrote:

> >> Shuah Khan (3):

> >>   lockdep: add lockdep_assert_not_held()

> >>   lockdep: add lockdep lock state defines

> >>   ath10k: detect conf_mutex held ath10k_drain_tx() calls

> >

> > Thanks!

> 

> Via which tree should these go?


I've just queued the lot for locking/core, which will show up in tip
when the robots don't hate on it.

Does that work for you?

Peter Zijlstra <peterz@infradead.org> writes:

> On Mon, Mar 01, 2021 at 10:45:32AM +0200, Kalle Valo wrote:

>> Peter Zijlstra <peterz@infradead.org> writes:

>> 

>> > On Fri, Feb 26, 2021 at 05:06:57PM -0700, Shuah Khan wrote:

>> >> Shuah Khan (3):

>> >>   lockdep: add lockdep_assert_not_held()

>> >>   lockdep: add lockdep lock state defines

>> >>   ath10k: detect conf_mutex held ath10k_drain_tx() calls

>> >

>> > Thanks!

>> 

>> Via which tree should these go?

>

> I've just queued the lot for locking/core, which will show up in tip

> when the robots don't hate on it.

>

> Does that work for you?


That's perfect, thanks! Just making sure that the patches don't get
lost.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

On 3/1/21 4:02 AM, Kalle Valo wrote:
> Peter Zijlstra <peterz@infradead.org> writes:

> 

>> On Mon, Mar 01, 2021 at 10:45:32AM +0200, Kalle Valo wrote:

>>> Peter Zijlstra <peterz@infradead.org> writes:

>>>

>>>> On Fri, Feb 26, 2021 at 05:06:57PM -0700, Shuah Khan wrote:

>>>>> Shuah Khan (3):

>>>>>    lockdep: add lockdep_assert_not_held()

>>>>>    lockdep: add lockdep lock state defines

>>>>>    ath10k: detect conf_mutex held ath10k_drain_tx() calls

>>>>

>>>> Thanks!

>>>

>>> Via which tree should these go?

>>

>> I've just queued the lot for locking/core, which will show up in tip

>> when the robots don't hate on it.

>>

>> Does that work for you?

> 

> That's perfect, thanks! Just making sure that the patches don't get

> lost.

> 


Awesome. Thank you.

thanks,
-- Shuah